1. Field of the Invention
The present invention relates to height adjustment apparatus for wheel assemblies and particularly to wheel height adjustment apparatus for use in pool vacuum equipment.
2. Prior Art
Pool vacuum equipment such as suction heads and associated apparatus is, of course, well known in the art. An example is the vacuum cleaner head in U.S. Pat. No. 4,376,320 which, however, has no means for varying the height of the head above the bottom surface of a pool. Generally speaking, a user will prefer the head be higher when using the device to clean vinyl flooring pools as compared to concrete pools where the suction cannot damage the pool. The '320 patent thus requires a variety of (1) different heads for different pools and (2) different suction equipment that may vary widely from pool to pool. See also U.S. Pat. No. 5,033,149 which provides a means to vary the height of the head but requires specially configured frame members on the head of two different types. Such an approach can be quite expensive and the particular approach used is also time-consuming.
Other height adjustment equipment includes very complex apparatus that is expensive and time consuming such as that disclosed in U.S. Pat. Nos. 2,776,446; 2,784,441; 2,836,430; 2,894,761; and 3,334,911, none of which are satisfactory.
What is desired is a height adjustment assembly that can be operated quickly and without the use of special tools. Furthermore, the assembly should be inexpensive and simple so as to reduce the possibility of the parts being jammed by debris as could easily happen with the excessive apparatus used in the prior art. Finally, the height adjustment apparatus should provide for adjustments in small increments and each wheel should be independently adjustable to allow a more customized height setting for a particular use. None of the prior art assemblies meet all of the above requirements.